The method and apparatus that is used to detect invalid inspiratory effort and improves patient-ventilator interaction
The cross reference of related application
It is the rights and interests of No. the 60/619th, 957, the U.S. Provisional Patent Application on October 20th, 2004 that the application requires the applying date, discloses its full content for your guidance at this.
Background technology
The present invention relates to be used for confirm and the nonsynchronous method of correction of a final proof patient-ventilator; For example auxiliary and comprise that the patient triggers the respirator that (triggered) breathes; Include but not limited to PSV, AC, AMV and two horizontal PS, and can protect air flue and show the effort of some autonomous respirations the patient, comprise the patient of dominant trait COPD, restricted, Combination condition of illness and need asynchronous between the common patient of assisted respiartion.
Problem definition
Patient with respiratory disorder or disease, particularly those acute attacks patient possibly not have enough breathing power to keep autonomous respiration and need mechanical assistance to breathe.For concrete condition; The task of selected respirator is different with type; And said respirator is different on the degree of breathing participation; From the complete passive controlled mechanical ventilation (CMV) of patient, to initiatively trigger behind the mechanical respiration the complementary respiratory form of sharing inspiratory effort with the patient by the patient.
Complementary respiratory form is by patterns of change, like parameter control (flow/volume/pressure), is incorporated into the auxiliary quantity of autonomous respiration and includes but not limited to: assist-control ventilation (AMV), synchronous intermittent mandatory ventilation (SIMV), and pressure support ventilalion (PSV).Therapeutic efficiency depends on that variable pressure/flow is supplied with and the synchronicity between patient's the autonomous respiration cycle.This it is essential respirator identification patient begins the ability that (trigger mechanism) made great efforts in autonomous respiration, this reaches positive flow threshold through the patient usually or minimum pressure threshold realizes.Can not reach the patient under the situation of this activation threshold value, the synchronicity of patient-ventilator is broken and possibly offset the benefit that any employing respirator is estimated.This phenomenon is known as invalid triggering and in multiple treatment, observes, but is modal in COPD.(" when receiving that high-level pressure support or assist control are breathed, 1/4th to 1/3rd of patient's lnspiratory effort may not trigger breathing machine." Tobin etc. (Tobin M, Jubran A, Laghi F.Patient-VentilatorInteraction.American Journal of Respiratory and Critical Care Medicine.163:1059-1063,2001.)).
The main cause of this antagonism is that expiratory gas flow is limited, the dynamic inflation of lung excessive and follows endogenous PEEP.Dynamically lung inflation excessively can be derived from the airflow obstruction at closed air flue rear, and machinery does not match with the nervous system expiration, or above-mentioned combination.In COPD, this is furtherd investigate, and in other pathology, carried out a small amount of degree but in various patients, observe.Mechanism is following: 1) among the COPD airway obstruction by causing like pathologic effects such as airway secretions, branch airway spasm and myxedemas.Gas-flow resistance increases in all scenario, and forces muscle to replenish the auxiliary expiration that causes the dynamic compression of air flue.2) equally under emophysematous situation, the compliance of respiratory system (compliance) possibly increase.The Emptying Rate of lung becomes bad, and effective normal expiration net cycle time (confirming by breathing negative feedback control) is not enough to cause the complete mechanical expiration.3) patient respiratory is limited occurs under the low volumetrical situation of lung, and therefore impels air flue closure and airflow obstruction, if particularly breathing rate is high.In all situations, end-tidal lung capacity (EELV) does not allow respiratory system to get back to the elastic equilibrium capacity, and external gas is limited in the lung, and promptly dynamically lung inflation is excessive.
The dynamic increase of EELV has several kinds of air-breathing influences of prevention in the patient of autonomous respiration.
Usually, drive the dynamic value P of the alveolar pressure of airflow direction at any time
Alv, in exhalation process, just remain, and decay to respect to atmospheric zero elasticity recoil pressure, i.e. P in end-tidal
Alv=P
se
-t/RC, P here
sIt is the static pressure plateau at air-breathing end.Yet exist under the over-drastic situation of dynamic lung inflation, the balance elastic recoil of respiratory system is not to obtain and P in end-tidal
AlvRemain just (intrinsic positive end expiratory pressure or PEEPi).For beginning to suck air-flow, alveolar pressure must be with respect to atmosphere for negative, so patient's respiratory muscle must at first overcome this remaining P before producing the suction air-flow
AlvOr PEEPi.Under this background, PEEPi is as IL.
Through make the respiratory muscle fiber from optimization length change to than short operation length and change diaphragm and the thoracic cavity between geometry arrangement, the pressure that the dynamic increase of lung capacity also can reduce respiratory muscle produces ability.
The increase of capacity also can make the work of lung be transformed into higher, in non-linear, the zone that compliance is littler of the capacity-pressure curve of end-tidal.Because the hardness of lung increases relatively, need bigger muscle effort and air-breathing power to make pulmonary's expansion here.
For to above-mentioned factor, respiratory muscle suffers tired and unable, finally causes the lung can not air inlet and aerofluxus.As a result, when the patient does inspiratory effort, reach small air-flow or pressure and change, and these inspiratory effort may not reach activation threshold value, therefore do not detected fully by respirator.
Fig. 1 is illustrated in the respirator of ideal operation under the PSV pattern (air-flow triggering).Express two complete breathing cycles.The air-flow of air flue opening part and pressure (PAO) are the available signals of respirator, and pleura pressure (PPL) is the external reference [1] that begins through counter-rotating expression patient inspiratory effort.After about 300 milliseconds of this incident, the patient obtains the required air-flow of trigger breathing machine [2] and IPAP is supplied to [3] subsequently.
On the contrary, Fig. 2 explains that the patient makes great efforts not by the detected result of respirator.Observe four patient's inspiratory effort among the data sequence PPL, have only first effort by respirator support [1] according to the explanation of front.Each inspiratory effort [2] subsequently all produces corresponding air-flow and rises, yet every kind of situation does not all reach activation threshold value [3] and the result is that respirator still remains under the EPAP.
, PV do not discern the also automatic surveying of the generation of the fruitless effort of record patient at present during interacting.(Varon J such as Varon; Et al.Prevalence of patientventilator asynchrony in critically ill patients [abstract] .Chest.106:141S; 1994) " antagonism index (index) " is expressed as the percentage ratio of the breathing that monitors that can not trigger, but the device of realizing this do not further specified.The author points out that index changes with the PEEP that applied, can supply with to eliminate and trigger antagonism through reducing pressure support or tidal volume in PSV or the AC pattern respectively, and point out that patient's waking state suitably influences index, promptly in the sleep when clear-headed index low.These visual reports mean that the equipment to the antagonism of the complementary respirator of statistical-reference increases significantly value, advise that in addition response actions can be used for the minimize loads that alleviates the antagonism and make breathing.
In perfect patient-ventilator interaction, respirator can with the electric pulse synchronous triggering that is derived from central nervous system.Though this concerning the mankind in fact and possibly be irrealizable ethically, be to realize the ultimate aim of synchronous patient-ventilator synchronicity near the time detecting patient's of incident inspiratory effort.
Further specify the triggering pressure that shows the support of pleura pressure and can improve the PV synchronicity, and the data among Fig. 1 and 2 are supported this theory.Yet this measuring method is derived from the sacculus dilating catheter that inserts esophagus, and the invasiveness of this level is to the outer application of ICU, like domestic, be unfavorable also be impossible.
The additive method of making great efforts in order to the accurate detection patient who assists the triggering of improvement respirator comprises the trigger sensitivity algorithm (USP 6626175) that uses external sensor (USP 6758216, and USP 6015388) and increase respirator inside.
The purpose of said method does not lie in the main cause that solves fruitless effort, i.e. excessive the and endogenous PEEP of the dynamic lung inflation of patient pulmonary existence.
A kind of more significant solution is to eliminate the PEEPi effect and reduce the decline that respiratory function is beginning to locate.Usually increase outside PEEP through respirator and obtain some successes, thereby when end-tidal, have balance between the pressure of mouth and the pressure in bubbles to offset PEEPi.Finally, improve patient-ventilator interaction through the counter-rotating amplitude that reduces the required pleura pressure of trigger breathing machine (making great efforts to produce) by respiratory muscle.That PEEP also flattens through additional front, nonventilated, as to be full of space increases functional residual capacity (FRC) and breathes compliance (in low capacity), the overall perfusion of raising (perfusion) and PaO
2
Therefore, applying PEEP counteracting PEEPi with the outside has reduced to breathe load and promoted respirator effectively to trigger.Yet the several reasons that the value of the PEEP that confirms to apply has difficulties is:
1) will cause dynamic lung inflation excessively to aggravate (and relevant issues) too much, even possibly in some patient, cause barotrauma.Show the existing level that the ideal value height depends on PEEPi.
2) when not having complete mechanical ventilation (the passive participation of patient), the static measurement of PEEPi is impossible, and because from the air-breathing and pressure effect expiration muscle group, kinetic measurement is by overestimate.
3) even can obtain absolute measurement, the PEEPi that breathes and breathe is a height change, and therefore the disposable measurement of outside PEEP is not enough.The supply of preferred continuous P EEPi measurement and servo adjusting PEEP.
The first step that solves first problem is a suitable ratio of deriving PEEP and PEEPi, and further dynamically lung inflation is excessive to avoid.Confirmed that additional PEEP is little to lung Emptying Rate and the dynamic over-drastic effect of lung inflation, surpassed marginal value P up to it
CritYet, the PEEPi and the P that need further research to measure
CritBetween exact relationship, if related words.Likewise, P
CritWhat ratio that is PEEPi is effective and harmless (between 75% to 90% change), and exist this whether with PEEPi dynamically or the relevant clinical discussion of quiescent value.In addition, the reliable and simple method of the dynamic excessive result's of lung inflation of measurement conduct PEEPi still remains to be developed under dynamic condition.Therefore, the most clearly scheme is to look problem than now actual understanding and assessment and decide.
United States Patent (USP) 6,588,422 have explained the method and apparatus of offsetting PEEPi in the supporting process in that the respiratory failure patient is breathed.This invention is intended to the adjustable PEEP that dynamically offsets PEEPi is supplied to the patient.It is through being similar to the problem that dynamic air flue compression degree has solved real-time and non-invasively measuring PEEPi of measuring.Two main method that realize this measurement are described: the ratio and 2 that 1) utilizes forced vibration technology (FOT) air-breathing conductivity of setting and expiration conductivity) the inspection exhaled air flow is to the shape of the curve of time.
Yet in fact these schemes have difficulties.Two kinds of technology have all adopted the limited pure and Utopian theoretical basis of possibility in reality.In addition, linear FOT demand makes utilizes slightly vibration to become necessary, and this possibly ignore other important nonlinear characteristics that occur in the moisture respiratory.Same method accuracy required in clinical protocol, data acquisition and analysis makes its environment at no supervision, i.e. applicability in the domestic ventilation is littler.
Therefore, the needs that can improve or eliminate in the above-mentioned defective one or multinomial method in the breathing technique have been produced.
Summary of the invention
The triggering signal that is used to detect miss that relates in one aspect to of the present invention, and the algorithm that therefore unrecognized patient makes great efforts in patient-ventilator (complementary) interaction process.A function of this algorithm is when the remarkable disturbance of airflow signal (the expression patient makes great efforts) takes place (pressure support or volume control) outside air-breathing the assisting of supplying with, to carry out record.The result of this algorithm is that these incidents are the labelling of reference with time, and it can be used as the patient-ventilator synchronicity and the successful statistics of treatment is therefore measured.
On the other hand; Possibly be final goal, be patient-ventilator antagonism to be minimized and reduce to breathe load, can correspondingly make index minimize (manually or servo adjusting)-(increase PEEP through changing ventilator parameter through taking measures; Reduce the pressure support; Or reduce tidal volume and supply with), and/or environmental factors (patient's states, medication).
Another aspect of the present invention is not the measuring by the detected patient's inspiratory effort of respirator of in patient-assisted respiartion machine interacts, taking place as demarcating.
Another aspect of the present invention provides the indication as the real patient respiratory ratio of the summation of the breathing of respirator supply and detected invalid patient's effort.
Of the present invention on the one hand is that servo adjusting through respirator minimizes invalid patient's inspiratory effort again, through with the next item down or more the realization more:
1) utilize statistical-reference to measure, servo adjusting is supplied with through the outside PEEP of respirator, for example after a succession of invalid triggering, incrementally strengthens the PEEP that applied so that index minimizes.
2) utilize statistical-reference to measure, servo adjusting is supplied with through the tidal volume of respirator, for example after a succession of invalid triggering, little by little reduces tidal volume and supplies with so that index minimizes.
3) utilize statistical-reference to measure, servo adjusting is supplied with through the pressure support of respirator, for example after a succession of invalid triggering, little by little reduces the pressure support so that index minimizes.
4) in the air-flow trigger breathing machine, to the polar fairness of air-flow (impartiality), directly trigger IPAP based on it with algorithm, for example after a succession of invalid triggering signal, activate once more and trigger so that index minimizes.
One side of the present invention is for the clinician reference corresponding to the following aspect of patient situation to be provided: 1) disease progression and acute exacerbation and/or 2) medication.
From the statistics of measuring, appearance or ratio like the triggering of miss can be used as: 1) trigger the unsettled alarm of expression conditions of patients, 2) as the guidance of suitable case control's program, like manual PEEP titration and/or 3) long record and follow the tracks of disease progression.
Another aspect of the present invention points to the inspiratory effort that is not detected and support by respirator with the COPD patient of complementary respirator is detected the method with calibration marks.
Another aspect of the present invention points to the method for the servo adjusting that the outside PEEP through respirator supplies with, and uses statistical-reference to measure, and for example after a succession of invalid triggering, strengthens the PEEP that applied so that index minimizes.
One side more of the present invention is pointed to based on the polar fairness of air-flow, activates this respirator air-flow trigger method.Algorithm can provide the indicating gage as variable air-flow activation threshold value, minimizes institute's requirement like index.
Other aspects of the present invention can be pointed to the next item down or multinomial: the guidance method of medication; The reference metric of the PEEP that clinicist's manual adjustment is applied; The indicating gage of disease progression is to predict and to warn imminent deterioration; And/or be used to trigger that alarm is adjusted the clinician to be provided with or management patient's method.
According to one embodiment of present invention, provide and detected the method for fruitless effort of being carried out the patient of mechanically ventilated by respirator, this method may further comprise the steps (i) respiratory air flow said respirator running back monitoring patient; (ii) produce the signal of the said air-flow of expression; (iii) remove the artifact in the said signal; (iv) monitor the disturbance of said signal; And (v) when said disturbance is remarkable, confirm to have taken place fruitless effort.
According to another embodiment of the invention, provide to be used to detect the system of fruitless effort that is carried out the patient of mechanically ventilated by respirator, this system comprises that (i) is used to monitor the device of patient's respiratory air flow after said respirator running; (ii) be used to produce the device of the signal of representing said air-flow; (iii) be used for removing the device of the artifact of said signal; (iv) monitor the turbulent device of said signal; And (v) when said disturbance is remarkable, be used to confirm to take place the device of fruitless effort; The wherein said turbulent device that is used to monitor said signal comprises the device that is used to detect local maximum.
According to still another embodiment of the invention; Provide to be used to detect the system of fruitless effort that is carried out the patient of mechanically ventilated by respirator, this system is included in the flow transducer that is used to monitor patient's respiratory air flow and produces the signal of the said air-flow of expression after the said respirator running; And the artifact that is used for removing said signal, monitoring has turbulent said signal, and when said disturbance is remarkable, has confirmed to take place the processor of fruitless effort; Wherein said processor is configured to monitor the disturbance of said signal through detecting local maximum.
According to a further aspect in the invention, the disturbance in the airflow signal of respirator running back appearance is classified according to categorizing system.Categorizing system is with fruitless effort and as coughing, swallowing with cardiogenic origin or beginning (cardiogenic origin) and wait other actions to differentiate.
According on the other hand, monitor fruitless effort and be used to measure compliance.In another form, use the measurement of fruitless effort to detect the outbreak that patient's situation worsens.
In another form, end expiratory positive pressure (PEEP) is adjusted according to the fruitless effort of measuring.In another form, the pressure support is adjusted according to the fruitless effort of measuring.In another form, tidal volume and/or air-flow are supplied with according to the fruitless effort adjustment of measuring.
According to another aspect of the invention, the respirator system that is used for the patient is provided, this system comprises the aerator of the source of breathable gas that produces pressurization; And the patient interface (like face shield, intubate, support (prong), blow (puff) etc.) of breathable gas being supplied with patient airway.Respirator system comprises processor (like common purpose computer etc.), program, algorithm, hardware and/or the software that is configured to carry out arbitrary method described herein.For example, based on the patient respiratory effort that measures that processor is confirmed, respirator is at least by partly control.
Of the present invention these with other aspects with describing in the DETAILED DESCRIPTION OF THE PREFERRED hereinafter or being conspicuous therein.
Description of drawings
Fig. 1 is the chart of explanation instance of synchronous patient-ventilator interaction under the PSV pattern;
Fig. 2 is the chart of the asynchronous patient-ventilator interaction of explanation;
Fig. 3 is the chart of the characteristic set of the single fruitless effort pattern of explanation;
Fig. 4 is the indicative flowchart according to the sophisticated method of embodiments of the invention general introduction monitoring antagonism;
Fig. 5 is the indicative flowchart that is used to monitor antagonism according to an embodiment of the invention;
Fig. 6 a-6c is the indicative flowchart that is used for the expiration phase of identification of breathing;
Fig. 7 is the indicative flowchart that is used to monitor antagonism according to an embodiment of the invention; And
Fig. 8 uses the chart of the operation result of embodiments of the invention realization for explanation.
The specific embodiment
Though following examples are pressed the procedural order explanation, it should be understood that this process can realize through non-linear, non-order or non-phase process, maybe can change the order of process.Likewise, although hereinafter is described whole process, some aspect of invention possibly only relate to the subclass of this process.
One side of the present invention is pointed to and is improved the patient-ventilator synchronicity, eliminates the demand to external sensor, measures endogenous PEEP (or through analogizing (analogy)), or the method for modification/complicated respirator internal trigger sensitivity algorithm.On the contrary; It is identified in the patient's effort do not supported that shows as specific characteristic in air-flow or the pressure signal; To their generation calibration marks, and will export alternatively, and force this error function to minimize in time through adjustment various respiratory machine/ambient parameter as error function.These adjustment or manual or servo adjusting possibly relate to PEEP and/or tidal volume and supply with (excessive for offsetting PEEP and reducing dynamic lung inflation), and trigger sensitivity.
In one embodiment, the algorithm of the triggering that is used to detect the miss of making great efforts corresponding to the patient is provided, this algorithm is not used the benefit of direct effort sensor.Just management of patients air road pressure is confirmed this.
As shown in Figure 2, the effort that is not supported is followed remarkable and unique disturbance in airflow signal [4], and this is common phenomenon.These disturbances:
Take place in the exhalation process after the respirator running with before triggering next time, promptly lack the air-breathing auxiliary of success;
Unnecessary by the positive draft sign, characterized but delay back draught.
Its " significantly " is that they distinguish like short arc phenomenons such as secretion or cardiogenic vibrations with noise or other mutually.
Its " uniqueness " be they with as swallow or cough waits the caused remarkable disturbance of other physiological phenomenons to distinguish mutually.
Some characteristics of airflow signal can be identified the characteristic as independent fruitless effort, and are as shown in Figure 3.Connect them in order and form characteristic set.In successive exhalation process, and behind the peak value that arrives exhaled air flow, the air-flow scattergram quickens to zero.This trend possibly be exponential for normal subjects, or for exhaled air flow limited to as if near linear attenuation.When on the expiration curve, fruitless effort occurring; In the counterblast of making great efforts beginning corresponding to muscle, possibly exist or not exist short, rapidly (with respect to the expiration baseline) slow down but the inclination [2] quite rapidly weak point, that get back to exhaled air flow scattergram baseline that always has local maximum [1] and be interrupted with local minimum [3].
The identification that relates in one aspect to the expiratory airflow signal of the present invention, and the remarkable and unique disturbance that belongs to this part signal of fruitless effort.This relates at least the peaked identification in part, and other continuous tilt.In addition, one side of the present invention is summarized the turbulent generic classifier that acts on airflow signal in the exhalation process, and said disturbance is relevant with physiological reason, comprise swallow, cough and cardiogenic vibration, so fruitless effort can more effectively be distinguished.High-grade flowchart text referring to Fig. 4.
One embodiment of the present of invention are with the remarkable local maximum detection fruitless effort that takes place in the exhalation process, and it can be implemented by following method.Fig. 5 has explained the flow chart of this process.
Preliminary signal processing may further comprise the steps:
1) adopt the monitor that comprises data collecting system and internal memory to write down the patient's of two respirators of using by oneself signal, this monitor can be a respirator self.These signals are air-flow (Q) and airway pressures (P) of mouth.
2) air road pressure signal passes through level and smooth/noise filter so that noise minimization.Such example is to have the phase place of making to lag behind and to minimize and cut-off frequency is 1 hertz a low order Butterworth low pass filter.
3) innocent omission (leak) backoff algorithm is applied to airflow signal, like United States Patent (USP) 6,152,129 (Berthon-Jones) are said.
4) first order derivative of calculated gas flow signal (Q ').
5) second derivative of calculated gas flow signal (Q ").
Three boolean's control signals are obtained by preprocessed signal:
1) index signal of expiration phase.This can realize through the method that adopts any amount; For example based on the polarity of air-flow to expiration phase classify (Fig. 6 (a)); Or optionally based on trigger and state that (therapy delivery) supplied with in the determined treatment of running incident to expiration phase classify (Fig. 6 (b)); Or to phase transformation threshold value determination pressure signal (Fig. 6 (c)) (, depending on auxiliary type) like ((IPAP or maximum pressure)-(EPAP or minimum pressure)) * 50%.Total control signal, C
Exp, be TRUE in exhalation process.
2) labelling shows the zero crossing in the first order derivative airflow signal.When Q '=0, master control signal C
Q 'Be TRUE, and the distortion (inflection) of sign airflow signal.
3) control signal guarantees that the distortion that a) is identified by step 2 is maximum; B) distortion has the qualified remarkable rising that is regarded as characteristic, distinguishes mutually with noise or cardiogenic air-flow.For example, this can be through realizing with respect to middle negative value (impartial negative), non-zero threshold alpha test second derivative airflow signal, but be not limited to its standard deviation or percentage ratio, is defined as:
Here
When less than-α, master control signal C
Q "Be TRUE.
Above-mentioned control signal quilt and (AND) are to derive combined index, here for each detected fruitless effort INDEX=TRUE.
An alternative embodiment of the invention detects fruitless effort as the characteristic set in the exhalation process, and this characteristic set comprises significant local maximum and continuous tilt, also has for the unique parameter of physiological reason.It can be implemented by following mode.
Preliminary signal processing may further comprise the steps:
1) adopt the monitor that comprises data collecting system and internal memory to write down the patient's of two respirators of using by oneself signal, this monitor can be a respirator self.These signals are air-flow (Q) and airway pressures (P) of mouth.
2) air road pressure signal passes through level and smooth/noise filter so that noise minimization.Such example is to have the phase place of making to lag behind and to minimize and cut-off frequency is 1 hertz a low order Butterworth low pass filter.
3) the innocent omission backoff algorithm is applied to airflow signal, like United States Patent (USP) 6,152,129 (Berthon-Jones) are said.
4) first order derivative of calculated gas flow signal (Q ').
5) second derivative of calculated gas flow signal (Q ").
Confirm the index signal of expiration phase.This can realize through the method that adopts any amount; For example based on the polarity of air-flow to expiration phase classify (Fig. 6 (a)); Or optionally based on trigger and the determined treatment condition of supplying of running incident to expiration phase classify (Fig. 6 (b)); Or to phase transformation threshold value determination pressure signal (Fig. 6 (c)) (, depending on auxiliary type) like ((IPAP or maximum pressure)-(EPAP or minimum pressure)) * 50%.Total control signal, C
Exp, possibly be TRUE in exhalation process.
Hereinafter is described and is illustrated among Fig. 5 set detection of combination perturbation features and pattern classifier.Fixed reference feature has been described and shown in Fig. 3.
Whether inspection expiration phase control signal is TRUE, determines whether that air-flow is carried out Disturbance Detection handles [1].
Following state variable and timing be initialised [2]:
1.max-detected-show and local maximum whether occurs
2.T
IE-take place from nearest local maximum, promptly the patient makes great efforts to begin to decay institute's elapsed time
3.potential_swallow-whether show the patient possibly swallow
4.T
SA-institute's elapsed time takes place from possible swallowing
5.dec-detected-show and whether detect significant inclination
Peak value expiratory airflow (PEF) is occurring early in the exhalation process continuously, and is carrying out Disturbance Detection [3] before through following formula calculating:
If (Q
i>Q
I-1), PEF=Q so
i
I representes sample order (sequence) here.Surpass about 200Lmin at PEF
-1Threshold value the time, think cough to occur and PEF is composed null value.
The preferential local maximum value tag [4] that detects, and through the zero crossing that descends on the first order derivative or fully the appearance of zero slope confirm:
Q '
i<0 and Q '
I-1>0, or Q '
i=0
Based on detected local maximum, state variable is represented and T with max-detected
11Reset.The local maximum of air-flow is stored as variable Q
a[5].
Check Q
aNearly null value to discern possible swallowing act [6].Swallowing of taking place in the expiration possibly be the disturbance that has similar characteristic set with fruitless effort.Yet this can be the temporary transient closure of air flue and asphyxia thus or zero air-flow stage by difference.The persistent period of estimating deglutition apnea is at least 500 milliseconds.If this assay is TRUE, state variable is represented with potential_swallow and deglutition apnea timing T
SAWith increasing sample time.
Until detecting remarkable inclination, the air-flow sampling of introducing is processed in this group circulation, at first identifies local maximum and starts the fruitless effort timing, and the probability of generation is swallowed in identification then, if swallow, starts the deglutition apnea timing.Two timing are repeating all to increase the amount that equates with sample time at every turn.
The appearance of the maximum through the variations in flow rate of successively decreasing (Q "=0) identification is significantly tilted [7], so its value is greater than middle negative value, non-zero threshold α, and the percentage ratio (as 33%) such as but not limited to standard deviation is defined as:
Here
N is with the sample number of the introducing air-flow gradual change, in long expiration or cyclic buffer.
In order to show the detection to this remarkable slant characteristic, state variable is represented [8] with dec-detected.
Whether in order to be that the result who swallows classifies to tilting, whether the timing of inspection deglutition apnea swallows 500 milliseconds of the times [9] greater than minimum expected, if greater than, resetting comprises the feature detection process of whole state variables and timing.
If detect inclination is not the result who swallows, and confirms next local minimum through the appearance of the zero crossing that increases in the first order derivative:
Q '
i>0 and Q '
I-1<0,
Based on detected local minimum, the decay that the whole persistent period of inclination and patient make great efforts is by clocking value T
IEProvide.For greater than 500 milliseconds value, characteristic set is considered to be difficult to carry out and be left in the basket [11] as fruitless effort.
The local maximum of air-flow is stored as variable Q
b, and magnitude of inclination is defined [12] and is:
|Declivity|=Q
a-Q
b
Magnitude of inclination is used for characteristic set is classified according to its physiological reason.Except fruitless effort, the more accurate inclination that occurs in physiological reason that remarkable disturbance is the most common and the exhalation process is secretion, cough and cardiogenic vibration (CGO).
At once the high frequency crepitation that takes place after can beginning as exhaling through the high-resolution airflow signal is observed patient's secretion.Signal is carried out can eliminating this crepitant existence to down-sampling or noise filtering, and can not eliminate the radio-frequency component in the fruitless effort.According to the filtering technique in the present embodiment, the less or not influence of excretory influence.
Cough is burst, the spastic contraction in thoracic cavity, causes gas to discharge fiercely from pulmonary.In expiration, air-flow can reach greater than 200L/min, considerably beyond the peak value of exhaled air flow.These threshold values are used to test magnitude of inclination [13].
In the obstructive patient of high-drag and low lung compliance, CGO if not fully can not, also be to be sent to mouth well.Their existence possibly weakened to down-sampling or noise filtering, or suppresses with the auto-adaptive filtering technique like the gated myocardial signal of ECG or pulse volume tracer.
Appear in the airflow signal and do not have under the repressed situation at CGO, can itself and fruitless effort be distinguished based on them less peak-paddy (peak-trough) or magnitude of inclination.The threshold value that adopts among this embodiment is 4L/min [14].
If magnitude of inclination is then thought fruitless effort has been taken place within total restriction.
After detecting fruitless effort with detect before the new local maximum of making great efforts corresponding to consecutive invalid, carried out a waiting time section [16].The minimum neural time (neural time) of this expectation based on air-breathing trial, promptly making great efforts is 500 milliseconds.
Fig. 8 shows the output of the embodiment of the invention.Two inspiratory effort that are not supported that are complementary with remarkable disturbance in the airflow signal are significantly, [1] and [2], and these are subsequently in time by algorithm identified and record.
These embodiment are examples of feasibility of the present invention, and these explanations should not be used as restriction.
Another aspect of the present invention relates to the real patient respiratory rate of index estimation of using fruitless effort.In one form, this will be through will accomplish the Calais with the quantity of the breathing of certain hour section internal respiration machine supply like the quantity of above-mentioned detected fruitless effort mutually.
Another aspect of the present invention relates to the antagonism of improvement patient-ventilator.Within periodic intervals or be used for a group calling and inhale adding up of circulation algorithm output and can be used as the indication of therapeutic effect with (the index statistics).Status of patient (high PEEPi at a large amount of misses; Acute attack) result's triggering; Or under the situation of incorrect respirator setting; Tolerance can promote to report to the police so that the clinician takes response actions (medication or PEEP/ pressure support/tidal volume are supplied with adjustment), and the effectiveness of this response actions of index statistical measurement before the reference.
Expand this notion,, promptly respirator is provided with PEEP/ pressure support/being adjusted in the respirator itself of tidal volume supply and can realizes automatization the response actions of index statistics.In addition, the servo adjusting of the continuous assessment of the effect of these adjustment and treatment will become possibility.
Though describe the present invention in conjunction with being considered to most realistic and most preferred embodiment at present; It should be understood that; The present invention should not be limited to the disclosed embodiments, on the contrary, is intended to cover multiple improvement within the spirit and scope of the present invention and is equal to setting.Likewise, above-mentioned various embodiments can combine with other embodiment to implement, and for example, some aspect of an embodiment can combine to realize another embodiment with some aspect of another embodiment.
For example, replace monitored airflow signal, at patient airway portal monitoring pressure signal.The characteristic set that can be applicable to a kind of form of pressure signal is correlated with the characteristic set of above-mentioned relevant air-flow on the contrary.For example, replace detecting gradient, the monitoring pressure signal obviously increases behind local minimum.
In addition; Although the present invention has special applications to the patient who suffers from COPD; It should be understood that the patient who suffers from other disease (for example congestive heart failure, diabetes, morbid obesity, apoplexy, stomach detour (barriatric) operation etc.) also can benefit from above-mentioned technology.